This paper presents a compact model of latchup taking into account design and process dependence. The new approach is more realistic and inspirited from the classical model. This model was used to confirm the single event latchup (SEL) robustness of D-Flip Flops (DFF) used in Readout Circuit of Infrared-sensors developed by Sofradir. SEL cross sections are presented by the mean of the monte Carlo tool MUSCA SEP3 in order to validate the new Latchup modeling approach.